1. Field of the Invention
The present invention relates to a tool changer of a machine tool that automatically changes a preceding process tool loaded in a spindle to a subsequent process tool selected from tools held by a tool magazine.
2. Description of the Related Art
A NC machine tool, for instance, includes a tool changer that selectively takes out, from a tool magazine, a tool corresponding to the machining contents designated in a NC machining program (subsequent process tool) and automatically changes a tool loaded in a spindle (preceding process tool) to the tool that is taken out.
More specifically, as a prearrangement for starting machining, an operator, for instance, stores tools to be actually used (actual use tool numbers T001, T002, . . . Tn) in pots (pot numbers P1, P2, . . . Pn) of a tool magazine and registers a correspondence relation between the pot numbers and the actual use tool numbers in a NC controller. Incidentally, it is also registered that the tool with the actual use tool number T001 is, for example, a tool for a 5 mm diameter drilling.
Generally, the numbers T001, T002, . . . of program-designated tools designated in the machining program only represent the machining order and do not correspond to the actual machining contents. Therefore, as the aforesaid prearrangement, the operator is required to rewrite the program-designated tool numbers to the actual use tool numbers corresponding to the machining contents by editing the machining program or to replace the tools stored in the pots of the tool magazine with the actual use tools corresponding to the machining contents and the machining order which are designated in the program.
However, there are problems that the editing in the former is troublesome and involves a possibility of error, and the latter takes a lot of time and trouble and has a great burden of the replacement work.
Japanese Patent Application Laid-open No. Hei 1-310834 discloses a tool controlling device that, when a tool having the number requested in a machining program is taken out from a pot of a tool magazine, compares the number of the taken out tool and the number of the requested tool, and when they match each other, starts the machining, but when they do not match each other, immediately stops the operation and displays abnormality.